Oli Scarff/Getty Images(LONDON) -- At least two people were killed and 13 others injured when a commercial helicopter crashed in central London during rush hour Wednesday morning.

Police were alerted to the incident on Wandsworth Road at around 8 a.m. local time, Scotland Yard said in a statement. Officials said the helicopter clipped a crane attached to one of the tallest residential towers being built in London and then spun out of control, slamming into the ground and setting cars and neighboring buildings on fire.

The helicopter's pilot was killed, and an additional person was killed by the crash, police said.

The London Ambulance Service said it treated seven patients on the scene and six others were taken to the hospital -- five with minor injuries and one with a broken leg.

All the fires caused by the crash have since been extinguished.

The helicopter, an Augusta 109, was on a scheduled flight from Surrey and had been diverted to nearby Battersea heliport, according a Metropolitan Police official, and was flying through low clouds and fog.

A warning, known as a Notice to Airmen, advised pilots to be on the lookout for a "high rise jib crane" with a height of 770 feet in central London attached to a 50-story residential building, the St. George Wharf Tower.

Boris Johnson, the mayor of London, tweeted on Wednesday, "Very saddened to learn of the fatalities & injuries in today's helicopter crash. My thoughts are with the victims & their families."